Quality of life “…. Health is physical, mental and social well-being and not merely the absence of disease or infirmity...” World Health Organization,

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Presentatie over: "Quality of life “…. Health is physical, mental and social well-being and not merely the absence of disease or infirmity...” World Health Organization,"— Transcript van de presentatie:

1 VAS, SG, TTO and PTO Measuring quality of life An Interactive Introduction

2 Quality of life“…. Health is physical, mental and social well-being and not merely the absence of disease or infirmity...”World Health Organization, 1947Extending health to well-being: Quality of lifeWhat is the definition of quality of life?

3 Many definitionsQuality of life is the degree of need and satisfaction within the physical, psychological, social, activity, material and structural area (Hörnquist, 1982).Quality of life is the subjective evaluation of good and satisfactory character of life as a whole (De Haes, 1988).Health related quality of life is the subjective experiences or preferences expressed by an individual, or members of a particular group of persons, in relation to specified aspects of health status that are meaningful, in definable ways, for that individual or group (Till, 1992).Quality of life is a state of well-being which is a composite of two components: 1) the ability to perform everyday activities which reflects physical psychological, and social well-being and 2) patient satisfaction with levels of functioning and the control of disease and/or treatment related symptoms (Gotay et al., 1992).An individual’s perception of their position in life in the context of the culture and values systems in which they live and in relation to their goals, expectations, standards and concerns (WHO Quality of life Groups, 1993).

4 No clear definition Researchers are free to chooseThe notion of measuring the quality of life could include the measurement of practically anything of interest to anybody. And, no doubt, everybody could find arguments supporting the selection of whichever set of indicators to be his choice…Andrews & Withey, 1976, page 6

5 No clear definition because…Different origins of researchClinical decision makingDoes the patient benefit from the treatment?Epidemiology (public health)what is the morbidity of the population?Health economicsIs it worth the money?

6 Common items in definitions:It is not the doctor who reportsQuality of life is subjective….“Given its inherently subjective nature, consensus was quickly reached that quality of life ratings should, whenever possible, be elicited directly from patients themselves. “ (Aaronson, in B Spilker (Ed): Quality of life and Pharmacoeconomics in Clinical Trails, 1996, page 180)Reports between proxies and patients vary.

8 How to measure quality of life form a clinical point of view?Choose itemsAre you able to walk one kilometer ?Do you feel depressed ?Choose response modeBinary yes / noMultiple (Likert) yes / at bid / hardly / noContinuous (Visual Analogue Scale) Always ————X—— NeverCombine items to dimensions of quality of lifeSum up the items belonging to one dimensionRescale sum on a scale from 0 to 100

13 Standard Gamble (SG) WheelchairLife expectancy is not important hereHow much are risk on death are you prepared to take for a cure?Max. risk is 20%wheels = (100%-20%) life on feetV(Wheels) = 80% or .80Main critiqueMore complicated than VAS and TTORisk aversion

27 Validity of PTO Health economists have a complex relation with PTOUnclear incorporation of equity (solidarity)Bad psychometric proportionsUnclear use of consensus by expert panelsNot preferredBut often used, as values for many health state are available

33 Difference in QALYs makes little difference in outcomeRichard Chapman et al, 2004“In a sizable fraction of cost-utility analyses, quality adjusting did not substantially alter the estimated cost-effectiveness of an intervention, suggesting that sensitivity analyses using ad hoc adjustments or 'off-the-shelf' utility weights may be sufficient for many analyses.”“The collection of preference weight data should […] should only be under-taken if the value of this information is likely to be greater than the cost of obtaining it.”

34 QALYs make a difference when:Chronic diseasePalliativeLong term negative consequences